1. Field of Invention
Embodiments of the invention relate, in general, to multicast streaming in a network. More specifically, embodiments of the invention relate to methods and systems for preempting control of multicast streaming.
2. Description of the Background Art
Data streaming is a method of transmitting data in a steady and continuous stream of packets from a source to a destination in a network. The stream of packets can include audio data, video data or a combination thereof. Data streaming transmits data in a compressed form over the network. Further, the transmitted data is played as soon as it arrives at the destination. There are two types of data streaming: unicast streaming and multicast streaming. Multicast streaming enables the transmission of identical data to more than one destination in the network. The Internet Group Management Protocol (IGMP) is a communication protocol that manages the process of multicast streaming in the network by managing the membership of Internet Protocol multicast groups. In the past, multicast streaming did not include advertisements while transferring main data to the multicast groups via a multicast stream. However, with the introduction of new technologies, multicast stream includes advertisements along with the main data. For example, a recent draft memo entitled Inserting Advertisements in IP multicast draft-akhunger-ad-insert-multicast-00, available at the Internet Engineering Task Force (IETF) web site (http://www.ietf.org/internet-drafts/draft-akhunger-ad-insert-multicast-00.txt) the disclosure of which is incorporated herein by reference, has kindled interest in the increased possibilities of controlling advertisements streaming when a national main event stream is interleaved with local/regional advertisements.
The advertisements can be inserted in the advertisement slots. The advertisement slots are decided by a primary source of data. Two types of advertisement slots can be included in the multicast stream. In the first type of advertisement slot, the primary source of data inserts the advertisements in the advertisement slots. These advertisements are received by all the members of the multicast group connected to the primary source of data.
The second type of advertisement slot is used to insert advertisements by secondary service providers, such as regional service providers. In this case, the main source of data informs a secondary service provider about the advertisement slots by sending an Ad-insert control packet. The Ad-insert control packet includes an Ad-insert message. The Ad-insert message indicates when the secondary service provider can take over the control of streaming from the primary source. Thereby, allowing the secondary service provider to utilize the specified time to insert its advertisements and send to the multicast group. However, in the case of emergencies such as hurricane, tornado or tsunami warning, the primary source may require to send emergency messages. Therefore, the primary source may require taking back control from the secondary service provider after sending the Ad-insert control packet. However, the primary source cannot take back control from the secondary service provider after sending the Ad-insert control packet.